Sealing label

ABSTRACT

A method, comprising:
         providing a combination of a package and a label attached to the package, wherein the label comprises a fluorescent substance,   illuminating the label with excitation light so as to cause the label to emit fluorescence light,   capturing an image of the label by using an imaging unit, and   detecting the position of the label by analyzing the captured image and/or detecting a degree of adhesion of the label by analyzing the captured image.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Finnish Application No. 20185610,filed Jul. 2, 2018, which is incorporated by reference herein in itsentirety.

FIELD

Some embodiments relate to adhesive labels.

BACKGROUND

A sealed package may comprise a package and a sealing label attached tothe package. An intact properly sealed package may be interpreted to bean indication that the product contained in the package is genuine. Thesealing label may be an adhesive label.

SUMMARY

An object of the invention may be to provide a sealing label. An objectmay be to provide a method for producing a sealing label. An object maybe a combination of a package and a sealing label attached to thepackage. An object may be an apparatus for monitoring position of alabel attached to a package. An object may be an apparatus for applyingsealing labels. An object may be a system for gathering data related tosealed packages.

According to an aspect, there is provided a label comprising:

-   a carrier layer and-   an adhesive layer,-   wherein the label comprises a wavelength conversion layer, which    comprises a fluorescent substance.

According to an aspect, there is provided a label comprising:

-   a carrier layer and-   an adhesive layer,-   wherein the label comprises a waveguiding wavelength conversion    layer, which comprises a fluorescent substance.

According to an aspect, there is provided a sealed package, whichcomprises a package and a label attached to the package, wherein thelabel comprises a carrier layer and an adhesive layer, wherein the labelcomprises a wavelength conversion layer, which comprises a fluorescentsubstance.

According to an aspect, there is provided a method comprising providinga combination of a package and a label attached to the package, whereinthe label comprises a carrier layer and an adhesive layer, wherein thelabel comprises a wavelength conversion layer, which comprises afluorescent substance,

-   the method further comprising:-   illuminating the label with excitation light so as to cause the    label to emit fluorescence light,-   capturing an image of the label by using an imaging unit, and-   analyzing the captured image.

According to an aspect, the method comprises checking whether theadhesive layer of the label is properly in contact with the package, bycomparing the captured image with reference data.

According to an aspect, there is provided an apparatus for detectingposition of a label with respect to package,

-   the apparatus comprising:-   a light source to provide excitation light,-   an imaging unit for capturing an image of a labeled package,-   one or more data processors to determine the position of the label    by analyzing the captured image.

The sealing label may comprise a wavelength conversion layer tofacilitate detection of the position of the label. The wavelengthconversion layer may, in turn, comprise a fluorescent substance tofacilitate detection of the position of the label.

The sealing label may comprise a modulating structure to spatiallymodulate radiance of fluorescence light emitted from the label. Themodulating structure may provide a predetermined pattern when the labelis illuminated with excitation light. The pattern may be e.g. targetpattern and/or a code. The pattern may be machine-detectable.

The modulating structure may be implemented e.g. by using opticallyfiltering regions, by using non-fluorescing regions, by varyingconcentration of the fluorescent substance at different transversepositions, and/or by varying thickness of a fluorescent material layer.

In an embodiment, the fluorescent substance may be distributed to arelatively thick material layer to optimize fluorescence quantum yieldand/or to optimize consumption of the fluorescent substance.

The label may further comprise a waveguiding layer, which comprises thefluorescent substance. The label may comprise a waveguiding layer, whichcomprises a fluorescent sub-layer. The label may comprise a waveguidingfluorescent layer. Illuminating the fluorescent substance withexcitation light may cause emission of fluorescence light. A part of thefluorescence light may be confined to the waveguiding layer by totalinternal reflection. The fluorescence light may be coupled out of thewaveguiding layer by out-coupling elements and/or by out-couplingfeatures. The fluorescence light may be coupled out of the waveguidinglayer e.g. by grooves, and/or perforations.

Each sealing label may be arranged to display a unique code, whenilluminated with the excitation light. Using the code may allowauthentication and/or tracking of the sealing labels. This may makestealing and/or falsification of the labels more difficult.

A sealed package may comprise a package and the sealing label attachedto the package. An intact properly sealed package may be interpreted tobe an indication that the product contained in the package is genuine.The sealing label may be applied e.g. in order to seal a packaging of amedicinal product. The package may contain a medicament. Checking and/orverifying proper sealing of the package may be important e.g. when thepackage contains a medicament.

The proper sealing of a package may be checked e.g. after the packagehas been closed and/or after the sealing label has been attached to thepackage. The proper sealing of a package may be checked e.g. before thepackage is forwarded to a next party involved in transportation and/orstorage of the packaged product.

The proper sealing of a package may be checked by using a monitoringapparatus, which illuminates the sealing label with excitation light,captures an image of the sealing label, and determines the position ofthe label by analyzing the captured image. The monitoring apparatus maye.g. provide an alarm signal if a label is determined to be missing orif a label is determined to be at a wrong position.

The sealing label may be substantially transparent. The transparentlabel may bring benefit in use. Clear film labels may enable stayingwith the current packaging design, i.e. there is no need to changeexisting artwork. A change of the visual appearance of the package mayrequire approval from an authority of state. Consequently, a change ofthe visual appearance of the package may be time consuming. Thetransparent label may provide a substantially no-label look, wherein itis not necessary to change or adapt the visual appearance of the packageaccording to the sealing label.

Using a transparent label may make it difficult to detect the presenceand/or position of a label attached to a package. For example, thepackage may have a substantially white color, and it may be difficult toreliably detect the presence and/or position of the transparent labelattached on the surface of the package. The label may comprise awavelength conversion layer to facilitate reliable detection of thelabel, in a situation where the label is illuminated with excitationlight. In particular, a substantially transparent label may comprise awavelength conversion layer to facilitate reliable detection of thelabel.

The combination of the package and the sealing label may comprise e.g.

-   a tamper evident feature,-   an overt or covert authentication feature, and-   a track and trace feature.

These features may allow authentication of the individual packagingthrough the entire supply chain. These features may together allowauthentication of the individual packaging through the entire supplychain.

The sealing label may be used as an anti-tampering device. The sealinglabel may also be called e.g. as tamper evident label. By tampering oropening or tearing off the sealing label the sealing label may becomeirreversibly broken and/or deformed to indicate that the sealing labelis no more intact.

The consumer should be the first person who opens the sealed package ina legal supply chain. The combination of the sealing label and thepackage may visually indicate to the consumer whether he is the firstperson who opens the sealed package. The sealing label may be arrangedto operate such that it is clearly evident to the customer whethertampering has occurred prior to authorized use or not.

The materials and the dimensions of the sealing label may be selectedsuch that it is difficult or impossible to remove the sealing label froma package without causing irreversible alteration of the label and/orthe package.

As an additional tamper evident feature, the sealing label may bearranged to cause visible cardboard tear in a situation where thesealing label is pulled away from the package. In particular, thedimensions and the materials of the sealing label may be selected suchthat pulling the sealing label from a varnished cardboard causesirreversible tearing of the varnished cardboard. In particular, thematerials and the dimensions of the sealing label may be selected suchthat it is difficult or impossible to remove the sealing label fromvarnished cardboard without causing irreversible alteration of the labeland the varnished cardboard. Pulling of the label may cause irreversibleelongation and/or delamination of the label, wherein pulling of thelabel may also cause that the surface of the packaging may be torn orripped off.

An individual sealed package may comprise a unique identifier (UI)and/or an anti-tampering device (ATD). The unique identifier may enableidentification and authentication of the individual sealed package, fromamong a high number of other substantially similar sealed packages. Eachpackage may comprise a different identifier. The identifier may be e.g.an alphanumerical code, a (one-dimensional) barcode, or atwo-dimensional barcode (e.g. QR code). The anti-tampering device mayallow detecting whether the individual sealed package has been openedand/or tampered.

A database may contain information about a plurality of packages. Thedatabase may contain data, which indicates e.g. the contents of apackage, manufacturer of the contents of the package, manufacturing dateof the contents of the package, packing date of the package, deliveryroute of the package, delivery dates of the package, and/or distributorsof the package. The database may contain information about where, whenand who has read the identifier of a package. The data associated withan individual package may be retrieved from the database e.g. based onthe identifier of said individual package. Using the identifier togetherwith data stored in the database may allow tracing the delivery routeand delivery times of the package. A distributor and/or a person may usethe identifier e.g. to check the authenticity of a product contained inthe package.

The identifier of a package may be read and used together with thedatabase to perform an authenticity check. The identifier of a packagemay be read e.g. at a storage or at a point of sale. The authenticitycheck may fail e.g. if:

-   a package associated with the identifier has not been produced,-   a package associated with the identifier should contain a different    product,-   a package associated with the identifier has not been transported to    said storage or to said point of sale,-   the same identifier has recently been read at a different location    which is not a part of the authorized supply chain, and/or-   a package associated with the identifier has already been handed    over to a consumer.

The labels may comprise a wavelength conversion layer, which comprises afluorescent substance. Thanks to using the wavelength conversion layer,the same monitoring apparatus may be used to detect the position of afirst label attached to a first package, and the position of a secondlabel attached to a second package. Thanks to using the wavelengthconversion layer, the same monitoring apparatus may be used to reliablydetect the positions of substantially transparent labels also in asituation where the color of the first package is different from thecolor of the second package. The first package may have e.g. asubstantially white color, and the second package may have a dark color.The average reflectance of the first package in the wavelength range 400nm to 700 nm may be e.g. higher than 80%, wherein the averagereflectance of the second package in the wavelength range 400 nm to 700nm may be e.g. lower than 40%.

The label may be arranged to provide a predetermined pattern, which maybe detected by using an imaging unit when the label is illuminated withexcitation light. The monitoring apparatus may be arranged to readand/or detect the pattern. The pattern may be e.g. a QR code.

In an embodiment, the monitoring apparatus may comprise one or moreoptical filters to increase contrast between the transparent label andthe surface of the package.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following examples, several variations will be described in moredetail with reference to the appended drawings, in which

FIG. 1 shows, by way of example, in a three-dimensional view, a packagesealed with a sealing label,

FIG. 2 shows, by way of example, applying a sealing label to a package,

FIG. 3 shows, by way of example, detecting the position of a label byusing a monitoring apparatus,

FIG. 4 shows, by way of example, an image of a package, wherein thelabel is in a wrong position,

FIG. 5 shows, by way of example, in a cross-sectional view, a sealinglabel which comprises fluorescent substance,

FIG. 6 shows, by way of example, wavelength conversion in the spectraldomain,

FIG. 7a shows, by way of example, in a cross-sectional view, a labelwhich comprises filtering mask regions,

FIG. 7b shows, by way of example, in a top view, the label of FIG. 7 a,

FIG. 7c shows, by way of example, an image of the label of FIG. 7a , ina situation where the label is illuminated with excitation light,

FIG. 7d shows, by way of example, spectral transmittance of a filteringmask region,

FIG. 8a shows, by way of example, in a top view, a label which comprisesa modulating structure,

FIG. 8b shows, by way of example, in a top view, a label which comprisesa modulating structure,

FIG. 8c shows, by way of example, in a top view, a label which comprisesa modulating structure,

FIG. 8d shows, by way of example, in a top view, a label which comprisesa modulating structure,

FIG. 9a shows, by way of example, in a cross-sectional view, a labelwhich comprises non-fluorescent regions,

FIG. 9b shows, by way of example, in a top view, the label of FIG. 9 a,

FIG. 9c shows, by way of example, an image of the label of FIG. 9a , ina situation where the label is illuminated with excitation light,

FIG. 10a shows, by way of example, in a cross-sectional view, a labelwhere the fluorescent layer has a first thickness at a first transverseposition and a second different thickness at a second transverseposition,

FIG. 10b shows, by way of example, in a top view, the label of FIG. 10a,

FIG. 10c shows, by way of example, an image of the label of FIG. 10a ,in a situation where the label is illuminated with excitation light,

FIG. 11a shows, by way of example, operation of a label which comprisesa homogeneous fluorescent layer,

FIG. 11b shows, by way of example, operation of a label which comprisesoptically filtering mask elements,

FIG. 11c shows, by way of example, operation of a label which comprisesnon-fluorescent regions,

FIG. 11d shows, by way of example, operation of a label which isarranged to provide a machine-detectable pattern,

FIG. 12a shows, by way of example, in a cross-sectional view, a label,which comprises a waveguiding fluorescent layer,

FIG. 12b shows, by way of example, in a cross-sectional view, couplinglight out of the waveguiding fluorescent layer via an edge of the label,

FIG. 12c shows, by way of example, in a cross-sectional view, couplinglight out of the waveguiding fluorescent layer by using an out-couplingelement,

FIG. 12d shows, by way of example, in a top view, a label, whichcomprises out-coupling elements,

FIG. 13 shows, by way of example, in a three-dimensional view,generating fluorescence light within a waveguiding layer, and couplingwaveguided fluorescence light out of the waveguiding layer,

FIG. 14a shows, by way of example, in a cross-sectional view, a labelwhich comprises a waveguiding fluorescent layer and out-couplingelements to couple light out of a waveguiding fluorescent layer,

FIG. 14a shows, by way of example, in a top view, the label of FIG. 14b,

FIG. 14c shows, by way of example, an image of the label of FIG. 14a ,in a situation where the label is illuminated with excitation light,

FIG. 15a shows, by way of example, monitoring the position of the labelby using a monitoring apparatus,

FIG. 15b shows, by way of example, monitoring the position of the labelby using a monitoring apparatus,

FIG. 16a shows, by way of example, in a cross-sectional view, awaveguiding fluorescent layer located between a carrier layer and anadhesive layer,

FIG. 16b shows, by way of example, in a cross-sectional view, awaveguide defined by ambient air and by an adhesive layer,

FIG. 16c shows, by way of example, in a cross-sectional view, awaveguiding layer defined by ambient air and by an adhesive layer,

FIG. 16d shows, by way of example, in a cross-sectional view, awaveguiding fluorescent layer located between a carrier layer and thesurface of the package,

FIG. 16e shows, by way of example, in a cross-sectional view, awaveguiding region defined by an air bubble,

FIG. 16f shows, by way of example, an image of the label of FIG. 16e ina situation where the label is illuminated with excitation light,

FIG. 17a shows, by way of example, in a top view, a label, which has avisually detectable indicator marking,

FIG. 17b shows, by way of example, in a top view, a label, which has avisually detectable indicator marking,

FIG. 17c shows, by way of example, attaching a label to a package,

FIG. 17d shows, by way of example, in a three-dimensional view, a sealedpackage,

FIG. 17e shows, by way of example, a damaged label and a damagedpackage, after the label has been pulled with a pulling force,

FIG. 18a shows, by way of example, in a cross-sectional view, a jointsealed by attaching a label to a substrate,

FIG. 18b shows, by way of example, in a cross-sectional view, a damagedlabel and a damaged substrate, after the label has been pulled with apulling force,

FIG. 19a shows, by way of example, elongation of a label as a functionof pulling stress,

FIG. 19b shows, by way of example, elongation of adhesive laminate webas a function of pulling force,

FIG. 20a shows, by way of example, in a three-dimensional view, anadhesive laminate web,

FIG. 20b shows, by way of example, in a three-dimensional view, a labelobtained by cutting from the adhesive laminate,

FIG. 21 shows, by way of example, units of a monitoring apparatus,

FIG. 22a shows, by way of example, monitoring the position of the labelby using a monitoring apparatus,

FIG. 22b shows, by way of example, first detector pixels and seconddetector pixels of the monitoring apparatus of FIG. 22 a,

FIG. 22c shows, by way of example, spectral response of the firstdetector pixels and spectral response of the second detector pixels,

FIG. 23a shows, by way of example, formation of detector signals of thefirst detector pixels, and

FIG. 23b shows, by way of example, formation of detector signals of thesecond detector pixels.

DETAILED DESCRIPTION

Referring to FIG. 1, a package 200 may be sealed with a label 100. Thepackage 200 and the label 100 may form a combination LC1 when the label100 is attached to the package 200. The combination LC1 may also becalled as a sealed package.

The package 200 may contain a product PROD1. The package 200 may containe.g. a substance PROD1 selected from the group consisting of medicine,cosmetic product, and foodstuff. In particular, the package 200 maycontain a medicament.

The package 200 may be e.g. a varnished cardboard box. The package maycomprise one or more substantially rectangular faces 202, 203. Thepackage may comprise a lid 202, which may be joined to a side of thepackage e.g. by a flexible hinge. The package 200 may comprise anopening joint 201. The sealing label 100 may be attached to the packagee.g. on both sides of the opening joint 20 (e.g. on the face 202 and onthe face 203). A consumer may access the product e.g. by breaking thesealing label 100 and by opening the joint 201.

In an embodiment, an opening joint 201 of the package 200 may be openedby breaking the label 100 without causing visually detectable damage tothe package 200. In an embodiment, the opening joint 201 cannot beopened without causing visually detectable damage to the package 200. Inan embodiment, the package may comprise a further opening portion, whichis arranged to be opened by breaking the package.

The package 200 may comprise one or more visually detectable markingsMRK1, MRK2, MRK3. The markings MRK1, MRK2, MRK3 may be e.g. printedmarkings formed on the surface of the package 200. The sealing label 100may be substantially transparent so that a marking MRK1 located beneaththe label 100 may be seen through the label 100, in a situation wherethe sealed package is illuminated with white light. The label 100 may besubstantially transparent such that one or more markings MRK1, MRK2,MRK3 located beneath the label 100 may be detected with the naked eyewhen illuminated with normal white light, which does not compriseultraviolet light.

For example, optical transmittance of the label 100 at the wavelength of650 nm may be higher than 80% in at least 90% of the area of the label100.

For example, at least 90% of the (one sided) area of the label 100 maybe substantially colorless when illuminated with normal white light,which does not comprise ultraviolet light.

The label 100 may comprise a fluorescent substance DYE1 to emitfluorescence light LUM1 in a situation where the label 100 isilluminated with excitation light EX1.

The label 100 may comprise a substantially transparent modulatingstructure STR1 to spatially modulate radiance of the fluorescence light,in a situation where the label 100 is illuminated with excitation lightEX1. The modulating structure STR1 may provide a machine-detectablepattern, which may be used for detecting the position of the label withrespect to the package.

The modulating structure STR1 may provide a target pattern UMRK1 (seee.g. FIG. 7c ), which may be easily recognized by an image recognitionalgorithm. The pattern may comprise e.g. a checkerboard pattern and/or astripe pattern.

The modulating structure STR1 may provide a pattern, which carriersinformation. The pattern may comprise e.g. a one-dimensional barcode, atwo-dimensional barcode, an alphanumerical code and/or a characterstring.

The modulating structure STR1 may make falsification of the sealinglabel more difficult. The modulating structure STR1 may operate as ananti-tamper feature. In an embodiment, each sealing label of amanufacturing batch may carry common identification code. In anembodiment, each sealing label may carry a different unique code, so asto allow identification and/or tracking of the sealing label. The codeof the label may make it more difficult to steal sealing labels and/orto make unauthorized copies of the sealing labels. The code of a sealinglabel of a package may also be read with a reader device in order toperform an authenticity check.

The label 100 may further comprise one or more visually detectablemarkings 90 to indicate authenticity and/or to indicate that the labelhas not been tampered (see e.g. FIG. 2). The marking 90 may be detectedwith the naked eye when illuminated with normal white light, which doesnot comprise ultraviolet light.

The marking 90 may be produced e.g. by printing with ink. The label 100may comprise a machine-readable pattern. The marking 90 may be formede.g. on the carrier layer 10. The marking 90 may also be located e.g.below the fluorescent layer of the label 100 such that the printedmarking (90) does not prevent detection of the fluorescence light LUM1of a machine-readable pattern.

The label 100 may further comprise one or more perforations PERF1 tofacilitate opening of the sealed package LC1 (see e.g. FIG. 15a ).

The label 100 may have a carrier layer 10, which comprises or consistsof plastic. The label 100 may comprise an adhesive layer 20. Theadhesive layer 20 may comprise pressure sensitive adhesive. The outersurface of the package 200 may e.g. comprise or consist of varnishedcardboard.

SX, SY and SZ denote orthogonal directions.

Referring to FIG. 2, the sealing label 100 may be attached to both sidesof an opening joint 201.

FIG. 3 shows, by way of example, an apparatus 500 for monitoring theposition of the label 100. The apparatus 500 may comprise a light sourceLS1 to provide excitation light EX1. The apparatus 500 may comprise animaging unit CAM1 to capture an image IMG1 of the label 100, when thelabel 100 is illuminated with the excitation light EX1.

The imaging unit CAM1 may be called e.g. as a camera. The camera CAM1may comprise an image sensor SEN1 and focusing optics FO1 to form animage IMG1 of an object by focusing light to the image sensor SEN1. Thefocusing optics FO1 may comprise e.g. one or more lenses. The imagesensor SEN1 may be e.g. a CMOS sensor or an CCD sensor. CMOS meanscomplementary metal oxide semiconductor. CCD means charge coupleddevice. The camera CAM1 may comprise an optical filter FIL1 to increasecontrast of the captured image IMG1.

At least a part of the label 100 may emit fluorescence light LUM1 whenilluminated with the excitation light EX1. The captured image IMG1 maycomprise partial images, which may be images of the regions of the labeland the package. The image IMG1 may comprise a partial image 100′ whichmay be an image of the label 100. The image IMG1 may comprise a partialimage AR1 which may be an image of a fluorescing region the label 100.The image IMG1 may comprise a partial image AR2, which may be an imageof the uncovered region of the package 200. The image may comprise ahigh contrast edge HE1 between the partial images AR1, AR2. Theapparatus 500 may analyze the captured image IMG1, and the position ofthe edge HE1 may be detected by an image recognition algorithm. Theimage IMG1 may comprise a partial image REF1, which may be an image of areference point REF1 of the package. The reference point REF1 may bee.g. at a corner of the package 200. The apparatus may be arranged todetect the position of the edge HE1 with respect to the reference pointREF1.

The apparatus may comprise one or more optical filters FIL1 to provide adesired spectral response of the combination of the camera CAM1 and theone or more filters FIL1. The apparatus may comprise one or more opticalfilters FIL1 to modify spectral response of the combination of thecamera CAM1 and the one or more filters FIL1. The method may compriseusing one or more optical filters FIL1 to define spectral sensitivityrange of the camera CAM1. The method may comprise using a filter FIL1 toincrease modulation depth (contrast) of the image IMG1 formed byfocusing the fluorescence light LUM1.

The filter FIL1 may be positioned e.g. between the label 100 and thecamera CAM1. The camera CAM1 may comprise the filter FIL1. The filterFIL1 may be e.g. absorptive filter and/or an interference filter. Thefilter FIL1 may be a band pass filter, a band rejection filter, or along pass filter. The spectral transmittance of the filter FIL1 may beselected to suppress the intensity of reflected and/or scatteredexcitation light, wherein the selected spectral transmittance of thefilter FIL1 may allow a significant part of the fluorescence light LUM1to propagate to the image sensor SEN1 of the camera CAM1. The filterFIL1 may increase the contrast (i.e. modulation depth) of the image IMG1by reducing a ratio of first intensity to second intensity, wherein thefirst intensity is the intensity of reflected and/or scatteredexcitation light impinging on the image sensor SEN1, and the secondintensity is the intensity of fluorescence light impinging on the imagesensor SEN1.

FIG. 4 shows, by way of example, a captured image IMG1 where the label100 is at a wrong position. The boundary REFBMD1 indicates a desiredposition of the label 100. The desired position of the label 100 may bespecified e.g. by reference data stored in a memory of the monitoringapparatus 500.

The monitoring apparatus 500 may compare the detected position of theboundary HE1 with the reference data in order to determine whether thelabel 100 is at a correct position or at a wrong position.

The monitoring apparatus 500 may e.g. provide an alarm signal when thelabel 100 is at a wrong position. The monitoring apparatus 500 may e.g.control operation of a labeling unit based on the detected position ofthe label.

The method may comprise:

-   providing a combination (LC1) of a package (200) and a label (100)    attached to the package (200), the label (100) comprising a    waveguiding structure (WG1), which comprises a fluorescent substance    (DYE1),-   illuminating the label (100) with excitation light (EX1) so as to    cause the label (100) to emit fluorescence light (LUM1),-   capturing an image (IMG1) of the label (100) by using a spectrally    selective imaging unit (CAM1), and-   analyzing the captured image (IMG1).

Analyzing the captured image (IMG1) may comprise e.g.:

-   detecting a pattern,-   recognizing a pattern,-   recognizing a pattern, which represents a machine-readable code,-   detecting the position of the label with respect to the package,-   detecting the position of the label with respect to the package by    comparing the captured image with reference data,-   detecting the position of the label with respect to the package by    comparing the captured image with one or more reference images,-   checking whether the adhesive layer of the label is properly in    contact with the package, by comparing the captured image with    reference data,-   checking whether the adhesive layer of the label is properly in    contact with the package, by comparing the captured image one or    more reference images.

Referring to FIG. 5, the excitation light EX1 may impinge on the label100. A part of the excitation light EX1 may be absorbed to thefluorescent substance DYE1 such that the fluorescent substance DYE1 mayemit fluorescence light LUM1.

The fluorescent substance DYE1 of the label 100 may absorb opticalenergy of the excitation light EX1. The optical energy of the excitationlight EX1 may optically excite the fluorescent substance DYE1. Thefluorescent substance DYE1 may release a part of the absorbed energy byemitting fluorescence light LUM1. A wavelength λ₂ of the fluorescencelight LUM1 may be longer than a wavelength λ₁ of the excitation lightEX1 also in a situation where the spectral intensity of the excitationlight EX1 at the wavelength λ₂ is zero. Thus, the label 100 may operateas a wavelength conversion device.

In particular, the label 100 may emit fluorescence light LUM1 at asecond different wavelength λ₂ in a situation where the label 100 isilluminated with excitation light EX1 at a first wavelength λ₁, andspectral intensity of the excitation light EX1 at the second wavelengthλ₂ is equal to zero.

A part of the excitation light EX1 may be reflected from the label 100as a reflected beam EX1 R.

A part of the fluorescence light LUM1 may escape out of the label 100through the upper major surface of the label 100.

The direction of an excitation light beam EX1 may be specified by aninput angle θ₁. The direction of the reflected beam EX1R may bespecified by a reflection angle θ_(1R). The direction of a light ray ofthe fluorescence light LUM1 may be specified by an angle θ_(k). Theangles θ₁, θ_(R), θ_(k) may indicate direction with respect to a surfacenormal SN of the label 100. The reflection angle θ_(1R) may besubstantially equal to the input angle θ₁.

The direction (θ_(k)) or directions of the fluorescence light LUM1 maybe different from the direction (θ_(1R)) of the reflected light EX1R.The label 100 may emit fluorescence light LUM1 to directions, which aredifferent from the direction of the reflected beam EX1 R. For example,the camera CAM1 of the monitoring system 500 may be positioned such thatthe camera CAM1 captures an image IMG1 by focusing the fluorescencelight LUM1.

For example, the camera CAM1 of the monitoring system 500 may bepositioned such that a major part of the reflected light EX1R isdirected away from the camera CAM1. This may reduce reflections, whichmay disturb detecting the position of the label 100.

The label 100 may optionally comprise a waveguiding fluorescent layer. Apart of fluorescence light LUM1 emitted inside the waveguiding layer maybe confined to the waveguiding layer by total internal reflection (TIR).The trapped fluorescence light LUM1 may be coupled out of thewaveguiding layer e.g. via an edge EDG1 of the label 100 and/or via anout-coupling element ELE1.

The fluorescent substance DYE1 may be mixed e.g. with the material of apolymer layer, with and adhesive and/or with printing ink. The carrierlayer 10 may comprise fluorescent substance, the adhesive layer maycomprise fluorescent substance and/or an additional material layer maycomprise fluorescent substance.

An optimum fluorescence yield and/or optimum consumption of thefluorescent substance may be attained when the concentration of thefluorescent substance is in an optimum range in a fluorescent layer. Inparticular, the concentration of the fluorescent substance may be keptbelow a predetermined limit in order to provide an optimum ratio of thefluorescence yield to the concentration of the fluorescent substance.The fluorescence yield may increase in a nonlinear manner withincreasing concentration of the fluorescent substance. The fluorescenceyield may saturate at high concentrations such that an increase of theconcentration causes a small or negligible increase of the fluorescenceyield.

The fluorescent substance DYE1 may be mixed with one or more othermaterials such that the molecules of the fluorescent substance DYE1 arespatially distributed in the thickness direction of the wavelengthconversion layer, in order to provide optimum fluorescence quantum yieldand/or in order to provide optimum consumption of the fluorescentsubstance.

The thickness of the wavelength conversion layer may be e.g. greaterthan or equal to 1 μm. The thickness of the wavelength conversion layermay be e.g. in the range of 1 μm to 200 μm. The thickness of thewavelength conversion layer may be e.g. in the range of 5% to 80% of thetotal thickness of the label 100.

The fluorescent substance DYE1 may be e.g. an organic dye.

The fluorescent substance DYE1 may be e.g. a product called as DCM([2-[2-[4-(dimethylamino)phenyl]ethenyl]-6-methyl-4H-pyran-4-ylidene]propanedinitrile).

The fluorescent substance DYE1 may be e.g. a perylene dye sold under atrade name “Lumogen F RED 305” by the company BASF.(N,N-Bis(2,6-diisopropylphenyl)-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxdiimide)

The fluorescent substance DYE1 may be e.g. selected from the group ofcoumarins. The fluorescent substance DYE1 may be e.g. coumarin.

The fluorescent substance DYE1 may be selected such that it is safe tohandle, when contained within the label 100. The fluorescent substanceDYE1 may be selected such that it is non-toxic when contained within thelabel 100.

FIG. 6 illustrates optical excitation of the fluorescent substance andspectrally selective detection of the fluorescence light.

The uppermost curve of FIG. 6 shows, by way of example, spectralintensity distribution of excitation light EX1. The excitation light EX1may be provided such that at least 90% of optical energy of theexcitation light EX1 may be at wavelengths shorter than a cutoffwavelength λ_(EXCUT). The spectral intensity may have a maximum at awavelength λ_(EXMAX). The symbol I(λ) denotes spectral intensity. Thesymbol I_(MAX) denotes maximum value of the spectral intensity.

The second curve from the top shows spectral absorbance A(λ) of thefluorescent substance DYE1. A_(MAX) denotes maximum value of thespectral absorbance A(λ).The spectral absorbance A(λ) may have one ormore peaks PEAK1, PEAK2. The spectral absorbance A(λ) may have a maximumvalue A_(MAX) at a wavelength λ_(AMAX).

The fluorescent substance DYE1 and/or the spectrum of the excitationlight EX1 may be selected such that the fluorescent substance DYE1 mayabsorb a sufficient fraction of the optical energy of the excitationlight EX1. The fluorescent substance DYE1 and/or the spectrum of theexcitation light EX1 may be selected such that the spectrum of theexcitation light EX1 at least partly overlaps the absorbance spectrum ofthe fluorescent substance DYE1.

Referring to the third curve from the top of FIG. 6, the fluorescentsubstance DYE1 may emit the absorbed energy as fluorescence light LUM1.The fluorescent substance DYE1 may absorb excitation light EX1 atshorter wavelengths, and the fluorescent substance DYE1 may emitfluorescence light at longer wavelengths. Thus, the fluorescentsubstance DYE1 may operate as wavelength conversion medium.

The fluorescent substance DYE1 may emit fluorescence light LUM1 also atwavelengths where the spectral intensity of the excitation light EX1 issubstantially equal to zero. The fluorescence light LUM1 may have amaximum at a wavelength λ_(FMAX). The wavelength λ_(FMAX) may besubstantially longer than the wavelength λ_(EXMAX). The wavelengthλ_(FMAX) may be substantially longer than the wavelength λ_(EXCUT).

Referring to the fourth curve from the top of FIG. 6, the spectrum offluorescence light LUM1 may be optionally modified by using an opticallongpass filter FIL1. The optical longpass filter FIL1 may have a cutoffwavelength λ_(DCUT) where the spectral transmittance T(λ) is equal to50% of maximum spectral transmittance T_(MAX). The filter FIL1 maysubstantially prevent propagation of spectral components at wavelengthsshorter than the cutoff wavelength λ_(DCUT) to the camera CAM1. Thefilter FIL1 may allow propagation of spectral components at wavelengthslonger than the cutoff wavelength λ_(DCUT) to the camera CAM1.

The lowermost curve of FIG. 6 shows, by way of example, the spectrum offiltered fluorescence light LUM1. The filtered fluorescence light LUM1may be obtained by filtering the fluorescence light LUM1 with theoptical longpass filter FIL1.

The camera CAM1 may be arranged to capture an image by focusing thefluorescence light LUM1 to an image sensor. The camera CAM1 may bearranged to capture an image by focusing the filtered fluorescence lightLUM1 to an image sensor.

The cutoff wavelength λ_(DCUT) may be selected e.g. such that the cutoffwavelength λ_(DCUT) is longer than or equal to the peak wavelengthλ_(EXMAX) of the excitation light EX1.

The cutoff wavelength XDCUT may be selected e.g. such that the cutoffwavelength λ_(FCUT) is longer than or equal to the cutoff wavelengthλ_(EXCUT) of the excitation light EX1.

Using the fluorescent substance DYE1 for wavelength conversion mayincrease contrast of the image IMG1 captured by the camera CAM1. Usingthe optical filter FIL1 may further increase contrast of the image IMG1,by reducing the contribution of reflected light.

The fluorescent substance DYE1 and/or the light source LS1 may beselected such that the fluorescent substance DYE1 has sufficientabsorbance at the peak wavelength λ_(EXMAX) of the excitation light EX1.The fluorescent substance DYE1 and/or the excitation light EX1 may beselected such that an emission peak of the excitation light EX1 at leastpartly overlaps an absorbance peak of the fluorescent substance DYE1.

The excitation light source LS1 may comprise e.g. a light emitting diode(LED), a laser, or a gas discharge lamp (e.g. a xenon flashlamp).

The light source LS1 may be e.g. a blue LED, wherein the peak wavelengthλ_(EXMAX) may be e.g. substantially equal to 460 nm. The cutoffwavelength λ_(EXCUT) may be e.g. substantially equal to 470 nm. Thelight source LS1 may be e.g. an ultraviolet LED, wherein the peakwavelength λ_(EXMAX) may be e.g. substantially equal to 380 nm, and thecutoff wavelength λ_(EXMAX) may be e.g. substantially equal to 390 nm.

Referring to FIGS. 7a and 7b , the label 100 may comprise a radiancemodulating structure STR1. The radiance modulating structure STR1 mayspatially modulate the radiance of the fluorescence light LUM1.

The modulating structure STR1 may comprise e.g. one or more filterregions C3. The filter regions C3 may attenuate or prevent propagationof the excitation light EX1 to the fluorescent layer CL1 of the label100, wherein the filter regions C3 may allow transmission of the emittedfluorescence light LUM1. The filter regions C3 may be e.g. opticallongpass filters or band rejection filters.

The modulating structure STR1 may comprise exposed regions RG1 andcovered regions RG3. The excitation light EX1 may interact with thefluorescent substance DYE1 in the exposed regions RG1. The regions RG3are covered with the mask filters C3, which attenuate or preventpropagation of the excitation light EX1 to the fluorescent substanceDYE1.

The label 100 may comprise a carrier layer 10 and an adhesive layer 20.The filtering regions C3 may be located e.g. between the carrier layer10 and the adhesive layer 20. The regions C3 may be applied e.g. byprinting. The label 100 may comprise a layer of fluorescent medium DYE1beneath the filtering regions C3. The adhesive layer 20 may comprisefluorescent medium DYE1. The filter regions C3 may be located above thefluorescent layer.

The fluorescent layer CL1 may have a thickness d_(CL1). The thicknessd_(CL1) of the fluorescent layer CL1 may be e.g. in the range of 1 μm to200 μm.

The filter regions C3 may be implemented e.g. by printing an opticallyfiltering ink. The filter regions C3 may be implemented e.g. by applyingoptically filtering polymer regions to the structure STR1.

Referring to FIG. 7c , the modulating structure STR1 may provide amachine-detectable pattern UMRK1, when illuminated with the excitationlight EX1, and when detected by the camera CAM1. The covered regions RG3may appear as dark regions AR3 in the captured image IMG1. The exposedregion RG1 may appear as a bright region AR1 in the captured image IMG1.

FIG. 7d shows, by way of example, spectral transmittance of a filterregion C3. The filter region C3 may be e.g. a long pass filter, whichattenuates or prevents transmission of the excitation light EX1, whereinthe filter region C3 may allow transmission of the fluorescence lightLUM1.

The filter regions C3 may also be ultraviolet-blocking filters, whichmay have spectral transmittance T(λ) greater than 80% in the wavelengthrange 460 nm to 700 nm, and which may have spectral transmittance T(λ)lower than 20% at wavelengths shorter than 400 nm.

Referring to FIGS. 8a to 8d , the modulating structure STR1 of the label100 may be selected to provide a pattern. The pattern may be e.g. atarget pattern and/or the pattern may represent a code.

The pattern may be provided e.g. by one or more of the following ways:

-   by spatial modulation of fluorescence yield (e.g. by spatial    modulation of concentration of fluorescent substance and/or by    spatial modulation of thickness of fluorescent layer).-   by spatial modulation of transmittance of an optically filtering    layer at a wavelength of the excitation light, wherein the optically    filtering layer may be positioned above the fluorescent layer,    and/or-   by spatial modulation of out-coupling efficiency

The pattern UMRK1 may be e.g. target pattern, which may be easily andreliably recognized by machine vision. The target pattern may be easilydistinguished from a background, which may comprise e.g. a printedsubstrate of the package. The target pattern may be e.g. a checkerboardpattern or a stripe pattern so as to facilitate machine recognition.

The pattern UMRK1 may also carry information. The pattern may be a code.The code may be e.g. a one-dimensional barcode, a two-dimensionalbarcode (e.g. QR code), an alphanumeric code and/or a character string.

The label 100 may comprise one or more perforated lines PERF1 tofacilitate opening of the package when the package is opened by thefinal customer. The position of the perforated line or lines PERF1 maysubstantially coincide with the position of the opening joint 201 of thepackage.

The perforated line PERF1 may also operate as an edge EDG1, which maycouple fluorescence light out of a waveguiding layer of the label 100(see FIG. 15a ).

The label 100 may further comprise a visually detectable indicatormarking 90, which may be easily detected when viewed with the naked eyein normal white light, which does not contain ultraviolet light. Theindicator marking 90 may be e.g. a conventional printed marking or ahologram. The indicator marking 90 may represent e.g. a trade markassociated with the product. An intact indicator marking 90 may visuallyindicate that the label 100 is a genuine label.

Referring to FIGS. 9a and 9b , the modulating structure STR1 maycomprise fluorescing regions RG1 and non-fluorescing regions RG3. Theconcentration of the fluorescent substance DYE1 in the non-fluorescingregions RG3 may be substantially lower than the concentration of thefluorescent substance DYE1 in the fluorescing regions RG1.

For example, the bottom side of the carrier layer 10 may be printed withfluorescent material, wherein the spaces remaining between thefluorescent regions may be filled with non-fluorescing material. Bothregions RG1, RG3 may be substantially transparent when viewed with thenaked eye in normal white light, which does not contain ultravioletlight.

Referring to FIG. 9c , the modulating structure STR1 of FIG. 9a mayprovide a machine-detectable pattern UMRK1, when illuminated with theexcitation light EX1, and when detected by the camera CAM1. Thenon-fluorescing regions RG3 may appear as dark regions AR3 in thecaptured image IMG1. The fluorescing region RG1 may appear as a brightregion AR1 in the captured image IMG1.

Referring to FIGS. 10a and 10b , the modulating structure STR1 maycomprise a fluorescent layer CL1, which has varying thickness. Thefluorescent layer may have a first thickness (d_(CL1)) at a firsttransverse position and a second thickness (d3) at a second transverseposition.

The transverse position may be specified e.g. by coordinates x,y,wherein the coordinate x may indicate position in the direction SX, andthe coordinate y may indicate position in the direction SY.

The label 100 may comprise transparent filler regions C3 so as toprovide constant total thickness for the modulating structure STR1. Thevarying thickness of the fluorescent layer may be provided e.g. byprinting the filler regions C3 or by applying transparent plastic filmto the regions RG3. For example, the bottom side of the carrier layer 10may be printed with non-fluorescing material, wherein the spacesremaining between the non-fluorescing regions may be filled withfluorescing material.

Referring to FIG. 10c , the modulating structure STR1 of FIG. 10a mayprovide a machine-detectable pattern UMRK1, when illuminated with theexcitation light EX1, and when detected by the camera CAM1. The thinnerregions RG3 may appear as darker regions AR3 in the captured image IMG1,wherein the thicker regions RG1 may appear as brighter regions AR1 inthe image IMG1.

Referring to FIG. 11a , the label 100 may comprise a carrier layer 10and an adhesive layer 20. The adhesive layer 20 may comprise fluorescentsubstance DYE1. The adhesive layer 20 may emit fluorescence light LUM1when illuminated with the excitation light EX1. Consequently, the image100′ of the label 100 may appear brighter than the image AR2 of theuncovered substrate SUB0 in the captured image IMG1. The common boundaryof the partial images 100′, AR2 may be easily detected as a highcontrast edge HE1. The position of the edge HE1 may be detected byanalyzing the image IMG1 with machine vision.

The substrate SUB0 of the package 200 may be fluorescent ornon-fluorescent. The substrate SUB0 may comprise a fluorescentsubstance. The fluorescent substance of the substrate SUB0 may bedifferent from the fluorescent substance DYE1 of the label 100. Thesubstrate SUB0 may emit fluorescence light LUM2 when illuminated withthe excitation light EX1. The spectrum of the fluorescence light LUM2emitted from the substrate SUB0 may be different from the spectrum ofthe fluorescence light LUM1 emitted from the label 100. The fluorescentsubstance DYE1 of the label may be selected such that the spectrum ofthe fluorescence light LUM1 is different from the spectrum of thefluorescence light LUM2, so as to provide sufficient contrast betweenthe label 100 and the substrate SUB0 in the captured image IMG1. Thecontrast between the label 100 and the substrate SUB0 in the capturedimage IMG1 may also be improved e.g. by using an optical filter FIL1,which suppresses the intensity of the fluorescence light LUM2, whencompared with the intensity of the fluorescence light LUM1. The filterFIL1 may be positioned e.g. between the label 100 and the camera CAM1.

Referring to FIG. 11b , the conversion efficiency of the label 100 maybe spatially modulated e.g. by providing one or more modulating regionsC3. The spatial modulation may provide a pattern UMRK1, which may beeasily detected by analyzing the captured image IMG1 when the label isilluminated with the excitation light EX1, wherein the pattern may besubstantially transparent when viewed with the naked eye in normal whitelight, which does not contain ultraviolet light. The filtering regionsC3 may be e.g. optical longpass filters, which may e.g. allowpropagation of red light and prevent propagation of blue light. Thefiltering regions C3 may be e.g. optical longpass filters, which maye.g. allow propagation of white light and prevent propagation ofultraviolet light.

The label 100 may comprise regions RG1, RG3. The region RG3 may denote aregion which completely overlaps a filtering region C3. The region RG1may denote a region which does not overlap a filtering region C3. RG2may denote an uncovered region of the substrate SUB0 of the package.

The image IMG1 may comprise partial images AR1, AR2, AR3. The image AR1may be an image of the region RG1. The image AR2 may be an image of theregion RG2. The image AR3 may be an image of the region RG3.

The common boundary between the regions RG1, RG3 may be detected as anedge HE23 between the partial images AR1, AR3. The common boundarybetween the regions RG1, RG3 may be detected as a high contrast edge HE1in the image IMG1.

The common boundary between the regions RG1, RG2 may be detected as anedge HE1 between the partial images AR1, AR2. The common boundarybetween the regions RG1, RG1 may be detected as a high contrast edge HE1in the image IMG1.

Referring to FIG. 11c , the modulating regions C3 of the structure STR1may also be implemented by varying the thickness of the fluorescentlayer and/or by varying the concentration of the fluorescent substanceDYE1 in a fluorescent layer.

Referring to FIG. 11d , the modulating regions C3 of the label 100 mayprovide a pattern UMRK1. The pattern UMRK1 may be detected in thecaptured image IMG1 when the label is illuminated with the excitationlight EX1, wherein the pattern UMRK1 may be substantially transparentwhen viewed with the naked eye in normal white light, which does notcontain ultraviolet light.

Referring to FIG. 12a , the label 100 may comprise a waveguidingconversion layer WG1. The waveguiding layer may comprise a fluorescentsubstance DYE1. The label 100 may be arranged to operate such that atleast a part of the fluorescence light LUM1 may be confined to thewaveguiding layer by total internal reflection (TIR). The waveguidinglayer may be defined by a first interface IF1 and by a second interfaceIF2. The refractive index n₁ of the waveguiding layer may be higher thanthe refractive index n_(2A) of the material layer below the waveguidinglayer so as to enable total internal reflection at the first interfaceIF1. The refractive index n₁ of the waveguiding layer may be higher thanthe refractive index n_(2B) of the substance above the waveguiding layerso as to enable total internal reflection at the second interface IF2.

For example, the label 100 may comprise a carrier layer 10, a claddinglayer CLD1, a waveguiding conversion layer WG1, and an adhesive layer20. The waveguiding layer WG1 may be located between the cladding layerCLD1 and the adhesive layer 20. The cladding layer CLD1 may be locatedbetween the carrier layer 10 and the waveguiding layer WG1. Therefractive index n_(2A) of the adhesive layer 20 and the refractiveindex n2B of the cladding layer CLD1 may be lower than the refractiveindex n₁ of the waveguiding conversion layer WG1. The waveguidingconversion layer WG1 may comprise a fluorescent substance DYE1.

Referring to FIG. 12b , at least a part of the fluorescence light LUM1may propagate along the waveguiding conversion layer WG1. The waveguidedfluorescence light LUM1 may be coupled out of the label 100 e.g. throughan edge EDG1 of the waveguiding conversion layer WG1. A camera CAM1 maybe arranged to form the image IMG1 by focusing light, which is coupledout of the edge EDG1. The image IMG1 may comprise a partial image of theedge EDG1 of the label 100. The partial image of the edge EDG1 may bebrighter than the surrounding areas of the image IMG1, when the label100 is illuminated with the excitation light EX1.

Referring to FIGS. 12c and 12d , the label 100 may comprise one or moreout-coupling elements ELE1, which may be arranged to couple fluorescencelight LUM1 out of the waveguiding conversion layer. The out-couplingelement ELE1 may be e.g. a light-scattering element or a diffractiveelement. A light-scattering element ELE1 may be e.g. a rough portion ofthe interface IF1 or IF2. A light-scattering element ELE1 may formede.g. by adding light-scattering particles to a selected region of thewaveguiding conversion layer. A diffractive out-coupling element ELE1may be e.g. a diffraction grating. The grating constant of the gratingand/or the orientation of diffractive features of the grating may beselected so as to direct the out-coupled light LUM1 towards the cameraCAM1.

The label 100 may comprise one or more out-coupling elements ELE1, whichmay be arranged to operate as marker features. The monitoring apparatus500 may be arranged to determine the position of the label 100 bydetecting the position of one or more marker features of the label 100.The out-coupling elements ELE1 may appear as bright areas in a capturedimage IMG1.

The out-coupling elements ELE1 of the label 100 may be arranged toprovide a pattern UMRK1. The pattern may be target pattern for machinerecognition and/or the pattern may carry information.

Referring to FIG. 13, the fluorescent substance DYE1 may emitfluorescence light LUM1 when illuminated with the excitation light EX1.A part of light LUM1 emitted in a waveguiding conversion layer WG1 maypropagate within the waveguiding conversion layer WG1. The propagatinglight LUM1 may be coupled out of the waveguiding conversion layer WG1 byan edge EDG1 of the label 100 and/or by an out-coupling element ELE1.The monitoring apparatus 500 may be arranged to detect the position ofthe EDG1 and/or the position of the out-coupling element ELE1 byanalyzing an image IMG1 of the label 100. The monitoring apparatus 500may be arranged to determine the position of the label 100 by detectingthe position of the edge EDG1 and/or by detecting the position of theout-coupling element ELE1.

Referring to FIGS. 14 and 14 b, the label 100 may comprise one or moreout-coupling elements ELE1 to couple light out of the waveguidingfluorescent layer CL1. The modulating structure STR1 of the label 100may comprise one or more out-coupling elements ELE1 to provide spatialmodulation of radiance. The element ELE1 may be e.g. a diffractive orrough portion of the surface of the fluorescent layer CL1. The elementELE1 may be formed e.g. by embossing, by adding light-scatteringparticles to the fluorescent layer and/or by making one or more holes inthe fluorescent layer CL1.

The label 100 may comprise one or more perforations PERF1. Theperforation PERF1 may operate as a light-out-coupling edge EDG1.

Referring to FIG. 14c , the out-coupling elements ELE1 and/or theperforation PERF1 may appear as bright partial images ELE1′, PERF1′ inthe captured image IMG1.

Referring to FIG. 15a , the monitoring apparatus 500 may comprise afirst light source LS1 to provide excitation light EX1 and a camera CAM1to capture a first image IMG1 when the label 100 is illuminated with theexcitation light EX1 at a time t₁. The light source LS1 may provide anexcitation light pulse at a time t₁. The camera CAM1 may have a field ofview VIEW1.

At least a part of the energy of the excitation light EX1 may convertedinto fluorescence light LUM1 in the waveguiding conversion layer WG1 ofthe label 100. The fluorescent substance DYE1 may emit fluorescencelight LUM1 when illuminated with the excitation light EX1. At least apart of the luminescent light LUM1 may be confined to the waveguidingconversion layer WG1 by total internal reflection at the interfaces IF1,IF2. A part of the excitation light EX1 may be coupled out of thewaveguiding conversion layer WG1 by an out-coupling element ELE1. Theout-coupling element ELE1 may be e.g. a scattering element and/or adiffraction grating. A part of the excitation light EX1 may be coupledout of the waveguiding conversion layer WG1 through an edge EDG1 of thelabel 100. The camera CAM1 may be positioned such that the camera mayform the image IMG1 by focusing the out-coupled light LUM1. The elementELE1, the perforation PERF1 and/or the edge EDG1 may appear as brightobjects in the captured image IMG1.

The modulating structure STR1 of the label 100 may generate a patternUMRK1. The generated pattern may appear in the captured image IMG1. Thestructure STR1 may comprise e.g. a waveguiding fluorescent layer,elements ELE1 and/or a perforation PERF1, and the generated pattern maycomprise bright partial images ELE1′ of the elements and a bright imagePERF1′ of the perforation PERF1.

The apparatus 500 may optionally comprise a second auxiliary lightsource LS2 to provide auxiliary illuminating light B0. The second lightsource LS2 may be arranged to provide auxiliary illuminating light B0.The spectrum of the auxiliary illuminating light B0 may be differentfrom the spectrum of the excitation light EX1. The auxiliaryilluminating light B0 may be e.g. white light for capturing aconventional photo IMG2 of the package 200. The light source LS2 mayprovide an auxiliary light pulse B0 at a time t₂. The camera CAM1 (or asecond camera) may capture an image IMG2 when the package 200 isilluminated with the auxiliary light pulse B0 at a time t₂. The imageIMG2 may comprise an image 200′ of the package 200. The boundary of thepackage 200 may be easily detectable in the image IMG2.

The use of the second image IMG2 may facilitate detecting the positionof the boundaries of the package 200. The apparatus 500 may be arrangedto analyze both images IMG1, IMG2 in order to determine the position ofthe label 100 with respect to the package 200.

The images IMG1 and IMG2 may be captured by using the same camera CAM1,by illuminating the package 200 with a first light pulse (e.g. EX1) andby illuminating the package 200 with a second light pulse (e.g. B0).

The camera CAM1 may comprise one or more optical filters FIL1 to providea desired spectral response.

The light source LS1 may comprise one or more optical filters FIL1 toprovide a desired spectral intensity distribution for the excitationlight EX1. The method may comprise using one or more optical filters todefine spectral intensity distribution of the excitation light (EX1)impinging on the label.

The light sources LS1, LS2 may provide light in a pulsed or continuousmanner. The use of pulsed light may e.g. allow time-multiplexedillumination of the label with different spectra, may allow shortexposure time of the camera, may allow imaging of a moving package, mayallow precise timing for capturing the image in case of the movingpackage, may reduce power consumption and/or may increase operating lifeof the light source.

Auxiliary imaging measurements may be performed by capturing anauxiliary image of the label 100 when the label 100 is illuminated withauxiliary light B0. The spectrum of the auxiliary light B0 may beselected such that the camera CAM1 may detect light (BOR) reflected fromthe label 100. The auxiliary light B0 may be e.g. white light or redlight.

The position of the excitation light source LS1 may be selected suchthat light EX1 reflected from the label 100 is not directed towards thecamera CAM1. The position of the excitation light source LS1 may beselected such that light EX1 reflected from the label 100 does notimpinge on the camera CAM1. The auxiliary light source LS2 may bepositioned such that the camera CAM1 may detect the light reflected fromthe label 100.

An air gap between the adhesive layer 20 and the substrate SUB0 mayincrease the reflection coefficient of the lowermost surface of theadhesive layer 20. The apparatus 500 may be arranged to monitor thereflection coefficient of the lowermost surface may measuring theintensity of light reflected from the lowermost surface of the label100. The apparatus 500 may be arranged to check whether the adhesivelayer 20 is properly attached to the substrate SUB0 of the package 200.The apparatus 500 may also be arranged to determine whether the label100 attached to the package 200 is wrinkled or flat. Abnormal intensityof reflected light may indicate that label 100 is not flat.

In an embodiment, the same light source LS1 may be arranged to provide afirst light pulse which has a first spectrum (of excitation light EX1)and a second light pulse which has a second spectrum (of auxiliary lightB0). The spectrum of the light may be changed e.g. by using one or moreoptical filters.

Referring to FIG. 15b , the monitoring apparatus 500 may comprise one ormore light sources LS1, LS2, and one or more cameras CAM1, CAM2. A firstcamera CAM1 may be arranged to capture a first image IMG1, which shows afirst side of the package 200 when the label is illuminated with theexcitation light EX1. The first camera CAM1 may be arranged to capture asecond image IMG2, which shows a first side of the package 200 when thelabel is illuminated with the auxiliary light B0. A second camera CAM1may be arranged to capture a second image, which shows a second side ofthe package 200.

Referring to FIG. 16a , the label 100 may comprise a waveguiding layerWG1 defined by a first interface IF1 and by a second interface IF2. Thefirst interface IF1 may be an interface between the waveguiding layerWG1 and a medium below the waveguiding layer WG1. The second interfaceIF2 may be an interface between the waveguiding layer WG1 and a mediumabove the waveguiding layer WG1. The first interface IF1 may besubstantially planar and the second interface IF2 may be substantiallyplanar. The waveguide WG1 may have a refractive index n₁. The mediumbelow the waveguide WG1 may have a refractive index n_(2A). The mediumabove the waveguide WG1 may have a refractive index n_(2B). Therefractive index difference (n₁-n_(2A)) between the waveguide WG1 andthe medium below the waveguide WG1 may be selected to provide totalinternal reflection (TIR1) at the first interface IF1 for fluorescencelight LUM1 propagating in the waveguide WG1. The refractive indexdifference (n₁-n_(2B)) between the waveguide WG1 and the medium abovethe waveguide WG1 may be selected to provide total internal reflection(TIR1) at the second interface IF2 for fluorescence light LUM1propagating in the waveguide WG1.

The waveguide WG1 may be located between a first substantially planarinterface IF1 and a second substantially planar interface IF2, whereinthe first interface IF1 may provide total internal reflection forfluorescence light LUM1 propagating within the waveguide WG1, and thesecond interface IF2 provides total internal reflection for fluorescencelight LUM1 propagating within the waveguide WG1.

The label 100 may comprise an intermediate waveguiding conversion layerWG1 (CL1), which may be located between the carrier layer 10 and theadhesive layer 20. The waveguiding conversion layer WG1 may be incontact with the carrier layer 10 and the adhesive layer 20. Therefractive index of the intermediate layer WG1 may be higher than therefractive index of the carrier layer 10 and higher than the refractiveindex of the adhesive layer 20. The waveguided fluorescence light LUM1may be coupled out by an edge EDG1 and/or by an out-coupling elementELE1.

The waveguiding layer or waveguide WG1 of the label 100 may be formed ofone or more sub-layers. The fluorescent substance DYE1 may bedistributed substantially evenly within the whole thickness of thewaveguiding layer WG1. Alternatively, the fluorescent substance DYE1does not need to be distributed over the whole thickness of thewaveguiding layer WG1. The waveguiding layer WG1 may comprise e.g. afirst sub-layer and a second sub-layer, wherein the composition of thefirst sub-layer may be different from the composition of the secondsub-layers. In particular, the waveguiding layer WG1 may comprise afirst fluorescent sub-layer, and a second non-fluorescent sub-layer.

Referring to FIG. 16b , the label 100 may comprise a waveguide formed ofone or more layers (e.g. 10, CL1). The waveguide WG1 may be asubstantially planar waveguide. The label 100 may comprise a waveguidinglayer WG1 formed of two or more sub-layers (e.g. 10, CL1). For example,the carrier layer 10 and a fluorescent intermediate layer CL1 maytogether form a waveguide WG1. The label 100 may comprise a fluorescentlayer CL1 located between the carrier layer 10 and the adhesive layer10. The fluorescent layer CL1 may comprise a fluorescent substance DYE1.The waveguide WG1 may be defined by a first interface IF1 and a secondinterface IF2. The first interface IF1 may be the interface between thefluorescent intermediate layer CL1 and the adhesive layer 20. The secondinterface IF2 may be the interface between the carrier layer 10 and theambient air AIR1. A lower sub-layer of the waveguide WG1 may have arefractive index n_(1A). An upper sub-layer of the waveguide WG1 mayhave a refractive index n_(1B). The first interface IF1 may have arefractive index difference n_(1A)-n_(2A). The second interface IF2 mayhave a refractive index difference n_(1B)-n_(2B). n_(2A) may denote therefractive index of the medium below the waveguide WG1. n_(2B) maydenote the refractive index of the medium above the waveguide WG1. Themedium below the waveguide WG1 may be adhesive of the adhesive layer 20.The refractive index n_(2A) may be equal to the refractive index of theadhesive layer 20. The medium above the waveguide WG1 may be ambient airAIR1. The refractive index n_(2B) may be equal to the refractive indexno of ambient air AIR1.

Referring to FIG. 16c , the carrier layer 10 may operate as awaveguiding conversion layer WG1. The carrier layer 10 may comprise afluorescent substance DYE1. The carrier layer 10 may be located betweenambient air AIR1 and the adhesive layer 20. The refractive index of thecarrier layer 10 may be higher than the refractive index of the adhesivelayer 20 and higher than the refractive index of air AIR1. Thewaveguided fluorescence light LUM1 may be coupled out by an edge EDG1and/or by an out-coupling element ELE1.

Referring to FIG. 16d , the adhesive layer 20 may operate as awaveguiding conversion layer WG1. The adhesive layer 20 may comprise afluorescent substance DYE1. The adhesive layer 20 may be located betweenthe carrier layer 10 and the substrate SUB0 of the package 200. Therefractive index of the adhesive layer 20 may be higher than therefractive index of the carrier layer 10 and higher than the refractiveindex of the substrate SUB0. The waveguided fluorescence light LUM1 maybe coupled out by an edge EDG1 and/or by an out-coupling element ELE1.

The method may comprise detecting a degree of adhesion of the label 100to the package 200, by analyzing the captured image IMG1. The method maycomprise measuring the degree of adhesion of the label 100 to thepackage 200. The degree of adhesion of the label (100) may be measuredby analyzing the captured image (IMG1). The degree of adhesion may bee.g. in the range of 0% to 100%. The value 0% may indicate that no partof the label is properly attached to the package. The value 100% mayindicate that the adhesive layer of the label is fully in contact withthe package. For example, a value 80% may indicate e.g. that the actualcontact area is only 80% of the intended contact area.

Referring to FIG. 16e , a waveguiding region may be used to indicatewhether a label 100 is properly attached to a package 200. The label mayalso be arranged to operate such that it provides a waveguidingfunctionality only one or more regions which are not fully in contactwith the package.

For example, the adhesive layer 20 of the label 100 may be arranged tooperate as a waveguiding layer in a situation where a harmful air bubbleBUB1 is trapped between the adhesive layer and the surface of thepackage 200.

A harmful air bubble BUB1 may sometimes remain trapped between theadhesive layer 20 of the label 100 and the surface of the package 200after the label 100 has been attached to the package 200. The degree ofadhesion of the label may be lower than 100% due to a trapped air bubbleBUB1. The method may comprise measuring the degree of adhesion of thelabel by utilizing a waveguiding property of the label.

The materials of the label and/or the package may be selected such thatrefractive index of the adhesive layer may be lower than the refractiveindex of the surface of the package 200, at the wavelength of thefluorescence light. The adhesive layer 20 may have a normal region NREG1where reflection coefficient of the lower surface of the adhesive layer20 for fluorescence light LUM1 is low, due to an interface IF0 betweenthe adhesive and the surface of the package 200. The same adhesive layer20 may have an abnormal region AREG1 where the reflection coefficient ofthe lower surface of the adhesive layer 20 for fluorescence light LUM1is high, due to an interface IF1 between the adhesive and the trappedair. The abnormal region AREG1 may provide total internal reflection(TIR) for fluorescence light LUM1 emitted from the label 100, whereasthe normal region NREG1 does not provide total internal reflection forfluorescence light LUM1 emitted from the label 100. Consequently, theemitted fluorescence light LUM1 may be waveguided in the label 100 inthe abnormal region, whereas the emitted fluorescence light LUM1 mayeffectively leak out of the label 100 at the abnormal region.

The label 100 may comprise a cladding layer CLD1 located between thecarrier layer 10 and the adhesive layer 20. The refractive index n_(2B)of the cladding layer CLD1 may be lower than the refractive index n₁ ofthe adhesive layer 20. Consequently, the abnormal region may operate asa waveguiding region also in a situation where the carrier layer is madeof a material (e.g. plastic), which has a high refractive index.

Referring to FIG. 16f , the abnormal region may be detected e.g. as adarker spot AREG1′ in a captured image IMG1. The fluorescence light LUM1leaking at the normal region NREG1 may provide a brighter region in theimage IMG1. The image AREG1′ of the abnormal region AREG1 may be e.g.darker than the image NREG1′ of the normal region NREG1.

The captured image (IMG1) may be compared with reference data (REFDATA1)e.g. in order to detect whether the adhesive layer of the label isproperly in contact with the package.

Referring to FIGS. 17a and 17b , the perimeter of the sealing label 100may be e.g. rectangular or circular. In case of a rectangular label 100,the length of the label may be e.g. greater than or equal to 30 mm, andthe width of the label may be e.g. greater than or equal to 15 mm. Incase of a circular label, the diameter of the label may be e.g. greaterthan or equal to 25 mm.

The label 100 may have an initial length L₀ and an initial width w₀. Inan embodiment, the perimeter of the label 100 may be used as a visualstretching indicator. A marking 90 of the label 100 may have an initiallength L₉₀ and an initial width w₉₀. In an embodiment, the marking 90may be used as a visual stretching indicator.

Referring to FIGS. 17c and 17d , the label 100 may be attached to apackage 200 to form a combination LC1. The combination LC1 may be callede.g. as a sealed package. The package may be e.g. a cardboard box. Thepackage may comprise one or more walls 203. The package may comprise oneor more covers 202. The package may comprise a lid 202, which may bejoined to a side of the package by a flexible hinge. The package 200 maycomprise an opening joint 201. When the joint 201 is not sealed with thelabel, the joint 201 may be opened and closed several times withoutcausing visual damage to the package. The label 100 may be attached tothe package 200 such that the opening joint 201 is located between twoattachment regions REG1, REG2.

The package 200 may comprise one or more markings MRK1, MRK2, MRK3, 290,which have been produced e.g. by printing or embossing. A surface of thevarnished cardboard may comprise one or more holograms.

Referring to FIG. 17e , the sealed package 300 may be opened e.g. bytearing the label 100 away from the package 200. The properties of thelabel 100 may be optionally selected such that the pulling the label 100away from the package 200 causes permanent stretching of the label 100and also visually alters the package 200. The attachment regions REG1,REG2 of the package may be converted into damaged portions DPOR1, DPOR2.The label 100 may have a final length L_(F) after it has been separatedfrom the package 200. The final length L_(F) of the label 100 may besubstantially greater than the initial length L₀ of said label 100. Thestretching of the label 100 may be easily detected by comparing one ormore dimensions of the label with a reference dimension. In anembodiment, one of the markings 290 of the package may define saidreference dimension. A method of checking the authenticity of the sealedpackage 300 may comprise comparing a dimension of the label 100 with areference dimension of a reference marking 290. In an embodiment,possible stretching of the label 100 may be detected by comparing amarking 90 of the label 100 with a marking 290 of the package.

In an embodiment, the label 100 may also be arranged to close anaperture (i.e. opening) of the package such that the aperture cannot beopened without causing permanent damage to the label 100 and to thepackage.

FIG. 18a shows a sealing label 100, which has been attached to a package200, which comprises varnished cardboard 230. The varnished cardboard230 may comprise cardboard material 231 covered with varnish 232. Thevarnished cardboard 230 may comprise a varnish layer 232 and cardboardmaterial 231. The adhesive layer 20 of the label 100 may be in contactwith the varnish 232.

The package 200 may comprise varnished cardboard 230, SUB0. Theoutermost surface of the varnished cardboard 230 may consist essentiallyof the water-based acrylate varnish. The varnished cardboard 230 may bee.g. fully coated folding boxboard approved for containing a medicament,wherein the varnish of the varnished layer 232 may be e.g. water-basedacrylate varnish

The label 100 may be attached to a first attachment region REG1 and to asecond attachment region REG2 of the package 200. The label 100 may beattached to the package such that an opening joint 201 of the package islocated between the first attachment region REG1 and the secondattachment region REG2. For example, the first attachment region REG1may be located on a side 203 of the package, and the second attachmentregion REG2 may be located on a lid or cover 202 of the package 200. Thelabel 100 may be attached to the package such that the label 100 cannotbe separated from the package without separating the label 100 from thefirst attachment region REG1 and from the second attachment region REG2.The label 100 may be attached to the package such that the opening joint201 cannot be opened without breaking the label 100, without damagingthe package, and/or without separating the label 100 from at least oneof the first attachment region REG1 and the second attachment regionREG2.

The varnished cardboard 230 may comprise a first layer 231 and a secondlayer 232. The first 231 layer may comprise cardboard material. Thefirst 231 layer of the varnished cardboard 230 may comprise cellulosefibers. The second layer 232 may consist essentially of varnish, or thesecond layer 232 may comprise cellulose fibers impregnated with thevarnish. The second layer 232 may be the outermost layer of thevarnished cardboard 230. The varnish may be e.g. water-based acrylatevarnish or UV-curable varnish. An UV-curable varnish may be applied tothe cardboard material and cured by using ultraviolet light. The varnishmay be approved for use in pharmaceutical packages. The varnishedcardboard 230 may be e.g. fully coated folding boxboard.

Referring to FIG. 18b , the properties of the label 100 may be selectedsuch that an attempt to separate the label 100 from the attachmentregion REG1 also causes visually detectable irreversible damage to thecardboard material 230. The label 100 may be pulled away from theattachment region REG1 by a pulling force F_(N). Pulling the label 100away from the first attachment region REG1 may convert the firstattachment region REG1 into a first damaged region DPOR1. Pulling thelabel 100 away from the second attachment region REG2 may convert thesecond attachment region REG2 into a second damaged region DPOR2 (FIG.17e ).

The pulling force F_(N) may be substantially perpendicular to theattachment region REG1. The pulling force may have a component F_(N),which is perpendicular to the attachment region REG1. The tensile stresscaused by the pulling force F_(N) in the cardboard material 231 mayexceed the breaking strength σ_(TS) of the cardboard material 231.

The damaged portion DPOR1 may be a pit (i.e. a crater). The cardboardmaterial 231 may be torn apart when the label 100 is pulled such that apiece of cardboard is separated from the package 200 and such that a pitDPOR1 is formed on the package 200.

FIG. 19a shows, by way of example, maximum elongation E_(M)(F_(M)) ofthe label 100 as the function of the maximum force F_(M), and finalelongation E_(F)(F_(M)) of the label (100) as the function of themaximum force F_(M).

The irreversible deformation of the label 100 may be easily visuallydetectable after the maximum pulling force FM has been greater than alimit value F_(LIM). The elongation E_(F)(F_(LIM)) at the limit valueF_(LIM) may be e.g. equal to 30%. The limit value F_(LIM) may be definedto be e.g. the value of the pulling force F_(M), which causes anelongation E_(F), which is equal to 30%.

F_(C) may denote the breaking force F_(C) of the cardboard material 231.The breaking force F_(C) may mean the minimum value of the pulling forceF_(M), which causes visually detectable permanent damage to thecardboard material 231 when the label 100 is pulled away from theattachment region POR1 of the varnished cardboard. The breaking forceF_(C) may mean the minimum value of the pulling force F_(M), which tearsa piece away from the cardboard material 231. Pulling the label 100 awayfrom the attachment region POR1 of the varnished cardboard with thebreaking force F_(C) may break the cardboard material 231.

F_(A) may denote the detaching force of the adhesive of the adhesivelayer 20. The detaching force F_(A) may mean the minimum value of thepulling force F_(M), which is sufficient to separate the label 100 fromthe varnished surface of the attachment region POR1. The detaching forceF_(A) may also be called e.g. as the de-bonding force.

The properties of the label 100 may be selected such that an attempt toseparate the label 100 from the varnished cardboard causes irreversibledamage both to the label 100 and to the varnished cardboard. Theproperties of the label 100 may be selected such that the label cannotbe separated from the varnished cardboard without irreversibly visuallydetectable stretching the label, and the label cannot be separated fromthe varnished cardboard without causing irreversible visually detectabletearing of the cardboard material.

The label 100 may have a high breaking strength in order to ensure thatthe cardboard is permanently damaged before the label is broken intopieces.

In case of a perforated label 100, the label 100 may have a highbreaking strength in order to ensure that the cardboard is permanentlydamaged before a non-perforated continuous portion of the label isbroken into pieces.

The label may be arranged to tear the cardboard material apart at thelower force than what is required to break the label.

The adhesive layer 20 may be firmly adhered both to the carrier layer 10and to the varnish 232 in order to ensure that the cardboard ispermanently damaged before the adhesive layer 20 is detached.

The label (100) may be suitable for use on a varnished cardboard (230,SUB0), the label (100) may comprise:

-   a carrier layer (10),-   an adhesive layer (20), and-   a wavelength conversion layer (WG1,CL1),-   wherein the thickness (d₁₀) of the carrier layer (10), the material    of the carrier layer (10), and the composition of the adhesive layer    (20) h selected such that:-   a minimum deformation force (F_(LIM)) of the label is smaller than a    first breaking force (F_(C)) needed to break the cardboard material    (231) of the varnished cardboard (230),-   a minimum detaching force (F_(A)) of the label (100) is greater than    the first breaking force (F_(C)), and-   a second breaking force (F_(BRK)) needed to break the label (100) is    greater than the first breaking force (F_(C)),-   wherein the first breaking force (F_(C)) is a first pulling force    which causes breaking of the cardboard material (231) in a situation    where the label (100) is separated from the varnished cardboard    (230) by pulling the label (100) with said first pulling force, and    the minimum detaching force (F_(A)) is a second pulling force which    is needed to separate the adhesive layer (20) of the label (100)    from the surface (SRF4) of the varnished cardboard (230) in a    situation where the label (100) is pulled with said second pulling    force.

The elongation (E_(BRK)) at break of the carrier layer (10) may be e.g.higher than or equal to 300%, advantageously higher than or equal to450%, and preferably higher than or equal to 500%. The carrier layer(10) may comprise e.g. polypropylene.

FIG. 19b shows, by way of example, maximum elongation E_(M)(σ) and finalelongation E_(F)(σ) of a label 100 as the function of stress σ of thecarrier layer 10 of the label 100 of FIG. 19 a.

σ_(LIM) may denote a stress which causes 30% final elongation. σ_(C) maydenote a stress which causes breaking of cardboard of a package. σ_(A)may denote a stress which is sufficient to detach the adhesive of thelabel from varnished cardboard. σ_(BRK) may denote a stress, whichbreaks the carrier layer into two or more pieces. The materials and/orthe thickness of the material layers of the label 100 may be selectede.g. such that σ_(A)>σ_(LIM), such that σ_(C)>σ_(LIM), such thatσ_(A)>σ_(C), and such that σ_(BRK)>σ_(C), so as ensure the label and thepackage exhibit visually detectable deformation.

Referring to FIG. 20a , a label web WEB1 may be produced. The web WEB1may be produced and/or transported e.g. as a sheet or as a roll. Aplurality of the labels 100 may be subsequently cut and/or separatedfrom the web WEB1. The materials of the layers 10, 20, and the thicknessof the layers 10, 20 may be selected such that the labels 100 may beformed by cutting from the web WEB1. The web WEB1 may comprise a releaseliner 30 to protect the adhesive layer 20, and/or to facilitate handlingof the web. The release liner 30 may have e.g. an anti-adhesion coatingto facilitate removal from the adhesive layer 20. The anti-adhesioncoating may be e.g. a silicone coating.

Producing a plurality of labels 100 may comprise:

-   producing a web WEB1, which comprises a carrier layer 10, an    adhesive layer 20, and modulating structures (STR1), and-   separating one or more labels 100 from the web WEB1.

Referring to FIG. 20b , labels 100 cut from the web WEB1 may comprisethe carrier layer 10, the adhesive layer, 20, a modulating structureSTR1 and a release liner 30. The release liner 30 may be removed beforethe adhesive layer 20 is brought into contact with the package 200.

In an embodiment, the carrier layer 10 of the label 100 may bepharmaceutical grade polypropylene film, the thickness d₁₀ of the filmmay be e.g. substantially equal to 65 μm, the elongation E_(BRK) of thefilm 10 at break may be e.g. substantially equal to 600%, and thetensile strength σ_(BRK) may be e.g. substantially equal to 36 N/mm² inthe machine direction (MD). The adhesive layer 20 may comprise e.g. awater-based polymer composition. The adhesive may be selected such thatthe adhesive is approved for use in pharmaceutical applications.

FIG. 21 shows, by way of example, units of a monitoring apparatus 500.The apparatus 500 may comprise one or more illuminating units LS1 toprovide excitation light EX1. The apparatus 500 may comprise one or moreilluminating units LS2 to provide auxiliary illuminating light B0. Theapparatus 500 may comprise one or more cameras CAM1, CAM2 to captureimages IMG1, IMG2. The apparatus 500 may comprise a clock to providetime information. The time information may be used e.g. fortime-stamping verification data, which may be stored e.g. in the memoryMEM3 and/or in a database. The apparatus 500 may comprise a memory MEM1for storing captured images IMG1, IMG2. The apparatus 500 may comprise amemory MEM2 for storing reference data REFDATA1. The apparatus 500 maycomprise a memory MEM3 for storing information, which indicates whetherthe label is at a correct position or not. This information may bestored in a database DBASE. The apparatus 500 may comprise a memory MEM4for computer program PROG1. The apparatus 500 may comprise a controlunit CNT1. The control unit CNT1 may comprise one or more dataprocessors. The computer program PROG1 may be configured to causeperforming one or more steps of the present method, when executed by theone or more data processors. The apparatus 500 may comprise acommunication unit RXTX1 for communicating data. The communication unitRXTX1 may be arranged to communicate e.g. with the Internet and/or withan process control system. The apparatus 500 may comprise a userinterface for providing information to a user and/or for receivingcomments from the user.

The reference data REFDATA1 may e.g. specify an acceptable range for theposition of a label 100. The captured image IMG1 may be compared withthe reference data REFDATA1 e.g. in order to determine whether the labelis at a correct position and/or whether the label is properly attachedto the package. The reference data REFDATA1 may e.g. specify anacceptable range for the brightness at one or more locations of acaptured image. The reference data REFDATA 1 may specify e.g. anacceptable range of brightness values for an edge, which appears in acaptured image of a label.

The reference data REFDATA1 may comprise e.g. one or more images of alabel which is properly attached to a package. The reference dataREFDATA 1 may comprise e.g. one or more reference images. A referenceimage may comprise e.g. an image of a label which is properly attachedto a package.

Referring to FIG. 22a , the monitoring apparatus 500 may comprise alight source LS12 to provide excitation light EX1, and the apparatus 500may comprise an imaging unit CAM12 to capture an image IMG10 of thelabel 100, when the label 100 is illuminated with the excitation lightEX1.

The imaging unit CAM12 may comprise an array of first detector pixels D1which have a first spectral response, and an array of second detectorpixels D2 which have a second different spectral response. The imagingunit CAM12 may comprise an image sensor SEN2. The image sensor SEN2 maycomprise an array of first detector pixels D1 and an array of seconddetector pixels D2. The imaging unit CAM12 may comprise focusing opticsF01 to form an optical image IMG0 of the label 100 on the image sensorSEN12 by focusing light. The image sensor SEN12 may convert the opticalimage IMG0 into a captured digital image IMG10. The captured image IMG10may comprise a first component image IMG11 and a second component imageIMG12. The first component image IMG11 and the second component imageIMG12 may be digital images.

The focusing optics FO1 may be arranged to focus reflected excitationlight EX1R and fluorescence light LUM1 to the image sensor SEN2. Thespectral response of the first detector pixels may be selected such thatthe first detector pixels may spectrally selectively detect fluorescencelight LUM1 and such that the first detector pixels may be substantiallyinsensitive to the reflected excitation light EX1R. The imaging unitCAM12 may be implemented also without using a common spectral filter forthe detector pixels D1, D2 of the imaging unit CAM12.

The captured digital image IMG10 may be e.g. a multi-color image, whichcomprises a first component image of a first color, and a secondcomponent image of a second color. The captured digital image IMG10 maybe e.g. an RGB image formed of a first component image representing thered color (R), a second component image representing blue color (B), anda third component image representing green color (G). The firstcomponent image IMG11 may be formed of detector signals provided by thefirst detector pixels D1. The second component image IMG12 may be formedof detector signals provided by the second detector pixels D2. A thirdcomponent image may be formed of detector signals provided by thirddetector pixels D3 (FIG. 22b ).

The imaging unit CAM12 may comprise a focusing unit FO1 and one or moreimage sensors SEN2. The label 100 and the package 200 may reflect and/orscatter a part of the excitation light EX1 to the imaging unit CAM12.The focusing unit FO1 may focus gathered light to the image sensor SEN2.The focusing unit FO1 may focus reflected light, scattered light, and/orfluorescence light to the image sensor SEN2.

The first detector pixels D1 may provide the first component image IMG11by detecting fluorescence light LUM1 emitted from the label 100 and/orfrom the substrate of the package 200. The first detector pixels D1 mayin a spectrally selective manner detect light LUM1 formed by thewavelength conversion.

The second detector pixels D2 may provide the second component imageIMG12 by detecting light (EX1, B0), which is reflected and/or scatteredfrom the label 100, and by detecting light (EX1, B0) reflected and/orscattered from the package 200. The second detector pixels D2 may detectreflected and/or scattered excitation light EX1. The second detectorpixels D2 may detect reflected and/or scattered auxiliary light B0. Thesecond component image IMG12 may represent a grayscale image of thecombination of the label and the package, wherein the contribution offluorescence light LUM1 to the second component image IMG12 may besuppressed.

The first component image IMG11 may be used together with the secondcomponent image IMG12, e.g. in order to reliably detect the relativeposition of the label 100 with respect to the package 200. For example aposition of the label may be determined from the first component imageIMG11, a position of the package may be determined from the secondcomponent image IMG12, wherein the position of the label may be comparedwith the position of the package in order to determine whether the labelis at a correct relative position or not.

The second component image IMG12 may be analyzed by using an imageanalysis algorithm e.g. in order to detect whether the shape of thepackage 200 matches with a predetermined shape or not. The secondcomponent image IMG12 may be analyzed e.g. in order to detect whetherthe dimensions of the package 200 match with predetermined dimensions ornot.

The package 200 may comprise a detectable pattern. The pattern may beformed e.g. by printing on the surface of the package. The pattern maybe e.g. an alphanumerical code. The pattern may be e.g. aone-dimensional barcode or a two-dimensional barcode. The pattern may bemachine-readable. The pattern may also be visually detectable. Thepattern of the package 200 may be detected and/or read from the secondcomponent image IMG12. The pattern of the package 200 may be detectedand/or read by image analysis of the second component image IMG12.

When using the first detector pixels and the second detector pixels, theposition of the label and the shape of the package may be determinedfrom the digital image IMG10 captured by the imaging unit CAM12. Whenusing the first detector pixels and the second detector pixels, theposition of the label and the shape of the package may be determinedeven from a single digital image IMG10 captured when illuminating thecombination LC1 with one illuminating light pulse (e.g. a single flashof light EX1).

The apparatus 500 may comprise a control unit CNT1. The control unitCNT1 may comprise one or more data processors. The computer programPROG1 may be configured to cause performing one or more steps of thepresent method, when executed by the one or more data processors of thecontrol unit CNT1.

Referring to FIG. 22b , the imaging unit CAM12 may comprise one or moreimage sensors SEN2. The image sensor SEN2 may comprise an array of firstdetector pixels D1, an array of second detector pixels D2, and an arrayof third detector pixels D3. The first detector pixels D1 may bearranged to spectrally selectively detect light which has a first color(e.g. red). The second detector pixels D2 may be arranged to spectrallyselectively detect light which has a second color (e.g. blue). The thirddetector pixels D3 may be arranged to spectrally selectively detectlight which has a third color (e.g. green). The image sensor SEN12 maybe e.g. an RGB image sensor.

The image sensor SEN12 may comprise a first array of first detectorpixels D1, and a second array of second detector pixels D2, wherein thefirst detector pixels D1 may be interlaced with the second detectorpixels D2. The first array of detector pixels D1 may be interlaced withthe second array of detector pixels.

The image sensor SEN12 may comprise a first array of first detectorpixels D1, a second array of second detector pixels D2, and a thirdarray of third detector pixels D3, wherein the first detector pixels D1may be interlaced with the second detector pixels D2 and with the thirddetector pixels D3.

The imaging unit CAM12 may comprise a plurality of first detector pixelsD1 to provide a first component image IMG11 by detecting fluorescencelight LUM1, wherein the imaging unit CAM12 may further comprises aplurality of second detector pixels D2 to provide a second componentimage IMG12 by detecting light EX1R reflected and/or scattered from thepackage 200, wherein the first detector pixels D1 have a first spectralresponse S_(D1)(λ), and the second detector pixels D2 have a seconddifferent spectral response S_(D2)(λ).

The imaging unit CAM12 may further comprise a plurality of thirddetector pixels D3, wherein the spectral response SD3(λ) may bedifferent from the spectral response S_(D1)(λ) of the first detectorpixels D1 and different from the spectral response S_(D2)(λ) of thefirst detector pixels D2.

The image sensor SEN12 may comprise e.g. a Bayer color filter array toprovide first spectral response S_(D1)(λ) for the first detector pixelsD1, to provide second spectral response S_(D2)(λ) for the seconddetector pixels D2, and to provide third spectral response S_(D3)(λ) forthe second detector pixels D3.

The image sensor SEN12 may be e.g. a CMOS sensor or an CCD sensor. CMOSmeans complementary metal oxide semiconductor. CCD means charge coupleddevice.

Referring to FIG. 22c , the spectral response of the second detectorpixels D2 may be different from the response of the first detectorpixels D1. The spectral response of the third detector pixels D3 may bedifferent from the spectral response of the first detector pixels D1 anddifferent from the spectral response of the second detector pixels D2.

In an embodiment, the imaging unit CAM12 may comprise a first imagesensor and a second image sensor. The first image sensor may comprisefirst detector pixels D1 which have a first spectral response S_(D1)(λ),and the second image sensor may comprise second detector pixels D2 whichhave a second spectral response S_(D2)(λ). Gathered light may be coupledfrom the focusing optics FO1 to the first image sensor and to the secondimage sensor e.g. via one or more beam splitters. Gathered light may becoupled from the focusing optics to the first image sensor and to thesecond image sensor e.g. via one or more spectrally selective beamsplitters.

Referring to FIG. 23a , the spectral response S_(D1)(λ) of the firstdetector pixels D1 may be selected such that the first detector pixelsD1 are insensitive to one or more spectral components of the excitationlight EX1. The first detector pixels D1 may have low response to theexcitation light EX1.

A signal provided by a single detector pixel D1 may be proportional toan integral of a function I(λ)S_(D1)(λ). The symbol I(λ) may denotespectral intensity of light impinging on the detector pixel D1, and thesymbol S_(D1)(λ) may denote the spectral response of the detector pixelD1. The integral may be calculated e.g. over a spectral range whichincludes spectral components of the light impinging on the detectorpixel D1.

The second curve from the bottom of FIG. 23a shows relative spectralresponse S_(D1)(λ) of the first detector pixels D1. S_(MAX) denotesmaximum value of the spectral response.

The imaging unit may gather fluorescence light, reflected light andscattered light from the combination of the label and the package. Thefocusing optics may focus gathered light to the image sensor. Somespectral components of the gathered light may contribute to the signalprovided by a detector pixel D1, and some spectral components of thegathered light do not contribute to the signal provided by the detectorpixel D1. The lowermost curve of FIG. 23a shows relative spectralcontribution I(λ)S_(D1)(λ) of the gathered light to a detector signal ofa first detector pixel D1. The lowermost curve of FIG. 23a may beobtained by multiplying the spectral intensity I(λ) of the gatheredlight with the spectral response function S(λ) of the first detectorpixels D1.

The first detector pixels D1 may be arranged to form a first componentimage IMG11 by detecting the fluorescence light LUM1.

The first detector pixels D1 may be insensitive to one or more spectralcomponents of the excitation light EX1. The first detector pixels D1 mayhave low response to the excitation light EX1.

Spectral components of the fluorescence light LUM1 may significantlycontribute to the detector signal obtained from the first detectorpixels D1.

The spectral response of the first detector pixels D1 may be selectedsuch that spectral components of the excitation light EX1 do notsignificantly contribute to the detector signal obtained from the firstdetector pixels D1.

Referring to FIG. 23b , the spectral response S_(D2)(λ) of the seconddetector pixels D2 may be selected such that the detector pixels D2 maydetect at least a part of the light (EX1R) which is reflected and/orscattered from the combination LC1. The second detector pixels D2 may bearranged to form a second component image IMG12 by detecting lightreflected and/or scattered from the combination LC1 of the label and thepackage.

The second detector pixels D2 may be insensitive to the fluorescencelight LUM1. The second detector pixels D2 may have low response tofluorescence light LUM1.

In an embodiment, the light source LS12 may be arranged to provideadditional illuminating light B0 together with excitation light EX1. Theadditional illuminating light B0 may be e.g. visible light. The lightsource LS12 may be arranged to provide an illuminating light pulse,which comprises excitation light EX1 and additional illuminating lightB0. For example, the illuminating light pulse (EX1+B0) maysimultaneously comprise ultraviolet excitation light (EX1) and visibleauxiliary light (B0).

The focusing optics FO1 may receive fluorescence light LUM1, reflectedauxiliary light B0 and/or scattered auxiliary light B0 from thecombination of the label and the package. The focusing optics FO1 mayfocus fluorescence light LUM1, reflected auxiliary light B0 and/orscattered auxiliary light B0 to the image sensor SEN2. In particular,the focusing optics FO1 may focus fluorescence light together with thereflected and/or scattered auxiliary light B0 to the image sensor SEN2.

The imaging unit CAM12 may be arranged to capture an image IMG10 whenthe combination LC1 of the label 100 and the package 200 is illuminatedwith said light pulse. The captured digital image IMG10 may comprise afirst component image IMG11 and a second component image IMG12. Thefirst detector pixels D1 may provide the first component image IMG11 bydetecting the fluorescence light LUM1. The second detector pixels D2 mayprovide the second component image IMG12 by detecting reflected and/orscattered auxiliary light B0. The first detector pixels D1 may have ahigher response to the fluorescence light LUM1, and a lower response tothe excitation light EX1. The second detector pixels D2 may have ahigher response to reflected and/or scattered auxiliary light B0, andthe second detector pixels D2 may have a lower response to thefluorescence light LUM1.

The first detector pixels D1 may spectrally selectively detectfluorescence light LUM1. The first detector pixels D1 may be insensitiveto the reflected and/or scattered excitation light EX1. The seconddetector pixels D2 may spectrally selectively detect reflected and/orscattered auxiliary light B0. The first detector pixels D1 may besensitive to the fluorescence light LUM1, wherein the second detectorpixels D2 may be insensitive to the fluorescence light LUM1. The seconddetector pixels D2 may be sensitive to the reflected and/or scatteredauxiliary light B0, wherein the first detector pixels D1 may beinsensitive to the reflected and/or scattered auxiliary light B0.

Various aspects are illustrated by the following examples.

Example 1. A label (100) comprising:

-   a carrier layer (10) and-   an adhesive layer (20),-   wherein the label (100) comprises a wavelength conversion layer    (CL1), which comprises a fluorescent substance (DYE1).

Example 2. A label (100) comprising:

-   a carrier layer (10) and-   an adhesive layer (20),-   wherein the label (100) comprises a waveguide (WG1), which comprises    a fluorescent substance (DYE1).

Example 3. The label (100) according to example 1 or 2 wherein thethickness of the wavelength conversion layer (CL1) is in the range of 5%to 80% of the total thickness of the label (100).

Example 4. The label (100) according to any of the examples 1 to 3wherein the thickness of the wavelength conversion layer (CL1) is in therange of 1 μm to 200 μm.

Example 5. The label (100) according to any of the examples 1 to 4wherein the fluorescent substance (DYE1) is an organic dye.

Example 6. The label (100) according to any of the examples 1 to 5comprising a substantially transparent modulating structure (STR1) toprovide a machine-detectable pattern (UMRK1) when the label (100) isilluminated with excitation light (EX1).

Example 7. The label (100) according to any of the examples 1 to 6wherein fluorescence quantum yield of the label (100) depends ontransverse position (x,y).

Example 8. The label (100) according to any of the examples 1 to 7wherein optical transmittance of the label (100) at the wavelength of650 nm is higher than 80% in at least 90% of the area of the label(100).

Example 9. The label (100) according to any of the examples 1 to 8wherein optical transmittance of the label (100) at the wavelength of550 nm is higher than 80% over a region, which represents 80% of thearea of the label (100).

Example 10. The label (100) according to any of the examples 1 to 9wherein optical transmittance of the label (100) in a wavelength rangeof 500 nm to 700 nm is higher than 80% over a region, which represents90% of the area of the label (100).

Example 11. The label (100) according to any of the examples 1 to 10,wherein the modulating structure (STR1) provides a target pattern forimage recognition.

Example 12. The label (100) according to any of the examples 1 to 11,wherein the modulating structure (STR1) comprises encoded data.

Example 13. The label (100) according to any of the examples 1 to 12,wherein the modulating structure (STR1) provides a one-dimensionalbarcode, a two-dimensional barcode, an alphanumerical code, and/or acharacter string.

Example 14. The label (100) according to any of the examples 1 to 13,wherein the modulating structure (STR1) has a first concentration of thefluorescent substance at a first transverse position and a secondconcentration of the fluorescent substance at a second transverseposition.

Example 15. The label (100) according to any of the examples 1 to 14,wherein a fluorescent layer of the modulating structure (STR1) has afirst thickness (d_(CL1)) at a first transverse position and a secondthickness (d3) at a second transverse position.

Example 16. The label (100) according to any of the examples 1 to 15comprising a visually detectable marking (90), which is located betweenthe fluorescent layer (CL1) and the adhesive layer.

Example 17. The label (100) according to any of the examples 1 to 16,wherein the modulating structure (STR1) comprises one or more spectrallyfiltering regions (C3) positioned above the fluorescent layer (CL1),wherein the filter regions (C3) locally prevent propagation ofexcitation light (EX1) to the fluorescent layer (CL1).

Example 18. The label (100) according to any of the examples 1 to 17,wherein the modulating structure (STR1) comprises one or more opticallong pass filter regions (C3) positioned above the fluorescent layer(CL1), wherein the filter regions (C3) locally prevent propagation ofexcitation light (EX1) to the fluorescent layer (CL1).

Example 19. The label (100) according to any of the examples 1 to 18,wherein the modulating structure (STR1) comprises one or moreUV-blocking filter regions (C3) positioned above the fluorescent layer(CL1), wherein the UV-blocking filter regions (C3) locally preventpropagation of UV light (EX1) to the fluorescent layer (CL1).

Example 20. The label (100) according to any of the examples 1 to 19,wherein the adhesive layer (20) comprises fluorescent substance (DYE1).

Example 21. The label (100) according to any of the examples 1 to 20,wherein the carrier layer (10) comprises fluorescent substance (DYE1).

Example 22. The label (100) according to any of the examples 1 to 21,wherein the label (100) is arranged to couple waveguided fluorescencelight (LUM1) out of an edge (EDG1) of the label (100).

Example 23. The label (100) according to any of the examples 1 to 22,comprising one or more out-coupling elements (ELE1) to couple waveguidedlight out of the waveguiding conversion layer (WG1).

Example 24. The label (100) according to any of the examples 1 to 23,wherein at least one of the out-coupling elements (ELE1) is rough(frosted) region or a diffraction grating.

Example 25. The label (100) according to any of the examples 1 to 24,comprising one or more perforations (PERF1).

Example 26. The label (100) according to any of the examples 1 to 25,wherein the adhesive layer (20) comprises a pressure sensitive adhesive(PSA).

Example 27. A sealed package (LC1), which comprises a label (100)according to any of the examples 1 to 27.

Example 28. A method for producing a label (100) according to any of theexamples 1 to 26.

Example 29. An adhesive laminate web (WEB1), which comprises a pluralityof labels (100), the labels being labels according to any of theexamples 1 to 26.

Example 30. A method, comprising:

-   providing a combination (LC1) of a package (200) and a label (100)    attached to the package (200), the label (100) being a label    according to any of the examples 1 to 29,-   illuminating the label (100) with excitation light (EX1) so as to    cause the label (100) to emit fluorescence light (LUM1),-   capturing an image (IMG1) of the label (100) by using an imaging    unit (CAM1), and-   analyzing the captured image (IMG1).

Example 31. The method of example 30, wherein the label (100) comprisesa waveguide (WG1), which in turn comprises a fluorescent substance(DYE1).

Example 32. The method of example 30 or 31, wherein said analyzingcomprises one or more of the following:

-   detecting a pattern,-   recognizing a pattern,-   recognizing a pattern, which represents a machine-readable code,-   detecting the position of the label with respect to the package,-   detecting the position of the label with respect to the package by    comparing the captured image with reference data,-   detecting the position of the label with respect to the package by    comparing the captured image with one or more reference images,-   checking whether the adhesive layer of the label is properly in    contact with the package, by comparing the captured image with    reference data, and/or-   checking whether the adhesive layer of the label is properly in    contact with the package, by comparing the captured image one or    more reference images.

Example 33. The method according to any of the examples 30 to 32,comprising determining the position of the label (100) by analyzing thecaptured image (IMG1).

Example 34. The method according to any of the examples 30 to 33,comprising capturing the image (IMG1) in a spectrally selective manner,by rejecting one or more spectral components of light (EX1R) reflectedand/or scattered from the label (100).

Example 35. The method according to any of the examples 30 to 34,comprising capturing the image (IMG1) in a spectrally selective manner,by using an optical filter (FIL1) to prevent propagation of one or morespectral components of light (EX1R) from the label (100) to the imagesensor (SEN1) of the camera (CAM1).

Example 36. The method according to any of the examples 30 to 35,comprising detecting fluorescence light (LUM1), which is coupled of awaveguiding layer (CL1) of the label (100) by an out-coupling element(ELE1) and/or by a perforation (PERF1).

Example 37. An apparatus (500) for detecting position of a label withrespect to package (200),

-   the apparatus (500) comprising:-   a light source (LS1) to provide excitation light (EX1),-   a camera (CAM1) for capturing an image (IMG1) of a labeled package,-   one or more data processors (CNT1) to determine the position of the    label (100) by analyzing the captured image (IMG1).

For the person skilled in the art, it will be clear that modificationsand variations of the devices and the methods according to the presentinvention are perceivable. The figures are schematic. The particularembodiments described above with reference to the accompanying drawingsare illustrative only and not meant to limit the scope of the invention,which is defined by the appended claims.

1. A label comprising: a carrier layer and an adhesive layer, whereinthe label comprises a wavelength conversion layer, which comprises afluorescent substance.
 2. The label of claim 1, wherein the labelcomprises a waveguide, which comprises a fluorescent substance.
 3. Thelabel of claim 1 wherein the thickness of the wavelength conversionlayer is in the range of 5% to 80% of the total thickness of the label.4. The label of claim 1, comprising a substantially transparentmodulating structure to provide a machine-detectable pattern when thelabel is illuminated with excitation light.
 5. The label of claim 4,wherein the modulating structure provides a target pattern for imagerecognition.
 6. The label of claim 1 wherein fluorescence quantum yieldof the label depends on transverse position.
 7. The label of claim 1,wherein optical transmittance of the label at the wavelength of 650 nmis higher than 80% in at least 90% of the area of the label.
 8. Thelabel of claim 1 wherein optical transmittance of the label in awavelength range of 500 nm to 700 nm is higher than 80% over a region,which represents 90% of the area of the label.
 9. The label of claim 4,wherein the modulating structure comprises one or more spectrallyfiltering regions positioned above the fluorescent layer, wherein thefilter regions locally prevent propagation of excitation light to thefluorescent layer.
 10. The label of claim 4, wherein the modulatingstructure has a first concentration of the fluorescent substance at afirst transverse position and a second concentration of the fluorescentsubstance at a second transverse position.
 11. The label of claim 4,wherein a fluorescent layer of the modulating structure has a firstthickness at a first transverse position and a second thickness at asecond transverse position.
 12. The label of claim 2, comprising one ormore out-coupling elements to couple waveguided light out of thewaveguiding conversion layer.
 13. The label of claim 1, comprising oneor more perforations.
 14. A sealed package, which comprises a packageand a label attached to the package, wherein the label comprises acarrier layer and an adhesive layer, wherein the label comprises awavelength conversion layer, which comprises a fluorescent substance.15. A method, comprising providing a combination of a package and alabel attached to the package, wherein the label comprises a carrierlayer and an adhesive layer, wherein the label comprises a wavelengthconversion layer, which comprises a fluorescent substance, the methodfurther comprising: illuminating the label with excitation light so asto cause the label to emit fluorescence light, capturing an image of thelabel by using an imaging unit, and analyzing the captured image. 16.The method of claim 15, wherein the label comprises a waveguide, whichin turn comprises a fluorescent substance, the method comprisingdetecting fluorescence light, which is coupled of the waveguiding layerby an out-coupling element.
 17. The method of claim 15, comprisingdetermining the position of the label by analyzing the captured image.18. The method of claim 15, comprising capturing the image in aspectrally selective manner, by using an optical filter to preventpropagation of one or more spectral components of light from the labelto the image sensor of the camera.
 19. The method of claim 15, whereinthe imaging unit comprises a plurality of first detector pixels toprovide a first component image by detecting fluorescence light, whereinthe imaging unit further comprises a plurality of second detector pixelsto provide a second component image by detecting light reflected and/orscattered from the package, wherein the first detector pixels have afirst spectral response, and the second detector pixels have a seconddifferent spectral response.
 20. The method of claim 15, comprisingchecking whether the adhesive layer of the label is properly in contactwith the package, by comparing the captured image with reference data.